Android sliding component suspended and fixed on the top effect

The effects to be achieved are as follows:

Scene: sometimes it is a component in the middle of the content, which is fixed on the top when sliding to the top.

Implementation ideas:

1. There are two sets of target buttons, which are placed at the top and in the middle of the content;

2. When the component in the middle of the content slides to the top bar position, control to display / hide the components at the top and in the middle (involving the component to obtain the position knowledge points on the screen);

Activity Code:

Key points analysis:

1. Obtain the height of the screen status bar and title bar in the onwindowfocuschanged() method (0 in the oncreate() method);

2. Because the onscrollchangelister() method of the Scrollview in the layout does not support ― > in the lower version API, the activity implements the onscrollchanged() interface method in the custom Scrollview ― > in this method, the display / hiding of components is realized;

Code for customizing Scrollview:

Then the layout file:

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